docs: def queryURL(self, xri, service_type=None):
          """Build a URL to query the proxy resolver.
  
          @param xri: An XRI to resolve.
          @type xri: unicode
  
          @param service_type: The service type to resolve, if you desire
              service endpoint selection.  A service type is a URI.
          @type service_type: str
  
          @returns: a URL
          @returntype: str
          """
          # Trim off the xri:// prefix.  The proxy resolver didn't accept it
          # when this code was written, but that may (or may not) change for
          # XRI Resolution 2.0 Working Draft 11.
          qxri = toURINormal(xri)[6:]
          hxri = self.proxy_url + qxri
          args = {
              # XXX: If the proxy resolver will ensure that it doesn't return
              # bogus CanonicalIDs (as per Steve's message of 15 Aug 2006
              # 11:13:42), then we could ask for application/xrd+xml instead,
              # which would give us a bit less to process.
              '_xrd_r': 'application/xrds+xml',
              }
          if service_type:
              args['_xrd_t'] = service_type
          else:
              # Don't perform service endpoint selection.
              args['_xrd_r'] += ';sep=false'
          query = _appendArgs(hxri, args)
          return query